Timing device



Jan. 21, 1947. I w. L. HUNT TIHIRG' DEVIfiE am June 29. 1943 3Shoots-sheaf 1 wzwrmz'm 5a orcomamon OF Jan. 21, 1947. w. L. HUNT2,414,467

TIMIN'G DEVICE Filed June 29, 1943 3 Sheets-Sheet 2 MOVABLE WITH CHANGECONDITIONED DEVICE Mentor:

- flaming/z Jan. 21, 1947. w L T 2,414,467

TIMING .DEVICE Filed June 29, 1943 3 Sheets-Sheet 3 MOVABLE WTH CHANGEOF CONDlTlON OF CONDITIONED DEVICE lll lllllllllllll Illllilllilll'IIIIIIIIIIIIIIIII. 1

.Ziakniorf y lierflalem memes he. 21, 1941 Walter Leslie Hunt,Philadelphia, Pa., assignor to Automatic Temperature Control 00., Inc.,

Philadelphia, Pa., a corporation of Pennsyl- Vania Application June 29,1943, Serial No. 492,674

13 Claims. (01.161-1) This invention relates to timing devices, andparticularly to variable timers either of stop or repeat cycles.

In the art of timers, which has been-very well explored in the past byvarious inventors and manufacturers, timing devices of great accuracyand of relative flexibility have been developed, whereby timed intervalsof long or short duration have been manifested by electric circuitcontrolling functions or the like, but so far as known in every case,the variation in the timed interval has been a pre-set manualfunctioning, as a necessary preliminary or prerequisite to initiation ofthe step, operation, or -method to. be timed. If through some change in.variable condition in the processing step or in the material beingworkedmr the like, the manually pre-set timing becomes incorrect, it istoo late, according to present timing systems, to change the timedinterval or predetermined cycle. In other words, previou timing methodsmade the processing step dependent upon a predetermined manually settimed interval, whereas the timed interval should be a mere function ofthe actual specific processing step in progress, as modified by theattributes or condition of the work involved.

It is among the objects of this invention: to provide a timing systemcoupled with a device vice; to improve the art of timers; to provide anovel form of timer: to provide an electronic susceptible to variationsin condition whereby the timer of accuracy and ease of operation; toprovide an electronically sensitive timer which is variable in settingthrough either manual or anatively coupled with a conditioned device foran tomatically predetermining the timed interval as a function ofcondition of the device, which may be either electrically ormechanically coupled and in which the timing-interval producer may be toany device of variable condition; and other obiects and advantages willbecome more evident as the description proceeds. In the accompanyingdrawings forming part oi. this description:

Fig.1 represents a diagrammatic illustration of tomatic means; toprovide a variable timer opera novel form of electronically controlledtimerhaving a repeat cycle according to one form of the invention;

Fig. 2 represents a diagrammatic perspective of a specific applicationoi. a form of invention to a variable weight condition;

Fig. 3 represents a somewhat diagrammatic fragmentary front elevation ofa mechanically controlled timer, representing a modification of theinvention;

Fig. 4 represents adiagrammatic section partially in full lines of themechanically controlled timer of Fig. 3.

Fig. 5 represents a diagram of a purely electronic timer of a stop cycletype according to a further modified form of invention;

Fig. 6 represents a fragmentary diagrammatic elevation of a governorcontrolled slidewire;

Fig. 7 represents a fragmentary diagrammatic section of a flow meterhaving an inductive coupling as the control of the bridge circuit; I

Fig. 8 represents a fragmentary diagrammatic section through aconditioned device with an expansion controlled element for varying thebridge circuit.

In a simple but preferred embodiment of the invention, a bridge circuitis provided, the respective actuating and actuated components of whichmay be widely spaced and respectively may be located in juxtaposition tothe instrumentalities which control the actuating component and thosewhich at a remotely different point are to be con Y the actuatingcondition-responsive element and ar mechanically or electrically coupledthereto so that the relative position of the arm and slidewire is adirect function of the instantaneous condition of a conditioned deviceor unit. In the purely illustrative form of device shown in Fig. 2,slidewire arm I5 is directly coupled with a weighing scale, to bedescribed, to position the slidewire as a function of the particularload on the scale. However embodied. it is the controlling iactor of thetimer, and is susceptible to variations in setting as functions of thevariations or fluctuations of any condition of a device, whether thecon-.

I ditions are of speed, in which the slidewire arm and slidewire arerelatively adjusted by a governor or the like as indicated in Fig. 6, orof humidity, pressure, temperature, linear dimensions, however varied,'su h aslength, height, width, orof motor 85, through common return 31to the line L2. The line 40 intersects'at A3 a relay coil connection 44leading to the plate 45 of the tube after passing through relay coil 28,

hardness, or deflection, or weight, or flow, as indicated in Fig. 7, orany other condition.

The bridge circuit is energized by the secondary I! of a transformer 18,the primary it or which is connected across the A. C. powerlines,respectively Li and L2. of the timing instrument has a limited extentdefined by the starting point'for each timing cycle designated as Min"at 2B, and having a maximum limit designated by 28, toward which eachtimed cycle starts,.but which is only attained if the predeterminedtimed interval requires such a maximumrange of movement. The actuatedslidewire pointer or arm 22, pivoted on a transverse axis 23, is shown,in a purely illustrative position, as slightly off the min or startingpoint 20, and is in electrical connection with the actuating slidewirearm or pointer it through the primary 24 or an input transformer 25. Itwill be understood that there will always be a current flowing throughthe primary 2% so long as the'a'rms I5 and 22 occupy disproportionatesettings on their respective slidewires, and that balance andtermination of the'iiow only occurs when the pointer 22 has been moved,illus The actuated slidewire l3 tube 21, which controls the energizationof the relay coil 28 and therefore both of the switch members-29 and33., .The upper switch member 29;;controls the particular desired loadsby means of a common terminal 30 and the alternate Poles 3] l and 32 ofthe load circuits, which are not shown in detail as any desiredinstrumentality or iris ntaiities are to be controlled by these loadcircuits. The lower switch member 33, in

the dropped out condition (shown). closes theline from power lead Li,switch 33, through pole terminal 36, through the in" running field 35 ofthe synchronous reversible motor 35, and through the common return 31 toline L2. The circuit throughv the ,out running field 39 of motor 36 willbe described later herein. The output shaft of the-reversiblesynchronous motor 36, after passingthrough suitable reduction gears orthe like (not shown) drives the actuated slide- ,wire arm 22 on axis23,111 one direction or the otherrelative to slide'wire l8, and theenergizetion of the field so drives the arm 22 from wherof slidewire[3,3, special limit switch 38 is provided, onejside of which connectswith power line Lij,..and "the other sideofjwhich connects throughailine' lli to theupper pole of the.

lower switch ofthe relay, and through a line 42 through the out" runningfield 39 of the As the start of a timing cycle is always from the pointmin'i at 20 on the slidewire l3, the actual initiation of the cycle isatthe instant that the switch 38 is made by the pointer or arm 22. At'thisjuncture of course the actuating pointer or arm l5 has been movedrelative to slidewire in either automatically as a function of theinstantaneous value of a particular condition of the conditioned devicewith which the timer is in operative association, or, in the broaderaspects of the invention, by a manual setting of the actuating pointerand slidewire. With the pointer 15 at some condition-functional positionrelative to its slidewire, say to the position indicated in Fig. l, andwith the'actuated slidewire pointer 22 at min setting, it willbe clearthat the flow across the bridge and through the primary 24 will beamaximum, so that ii the plate circuit were closed, it too would be at amaximum. The closing or the switch 38 actually closes the plate circuitso that it flows from line Li, switch 38, connectors so, 54, relay coil28, plate 45, cathode connector cc, to the other power line L2. Thus,the closing of the switch 38 instantaneously energizes the relay coil 28which snaps in, and the lower switch member 32 thereof successivelybreaks the circuit through the "in field 35 of the motor 36 by leavingpole 36, and then makes the circuit through the out field 39 of themotor by engagingpole 4|. The power circuit through the "ou field willbe clear, as with the relay in the circuit is from line LI, connector 48and 41, switch 33, pole or contact M, connector 42, out

field 39 of the motor, through the common return 31 to the line L2. Itis to be noted that the completion of the power circuit through the outfield or he motor pursuant to movement of the relay in, is accompaniedby a continuation of the established plate circuit holding the relayin," because the plate circuitis then from the line Ll through thefilament connection 68 and connector 61 to switch 33, contact 4!,connector to, relay coil 28, plate 65, through the cathode connector 26to the line L2. Thus, the relay is held in by the energization of thecoil 28 as long as any current flows across the bridge through the moreor less slight modification of the position of pointer 22 because of theexistence or resistance it in side connector H of the bridge circuit,the progress from maximum current flow tion of the flow through coil 26represents a timed interval comprising one-half of the total cycle ofthe timer.

If it be assumed that the condition of the device controlling theactuating pointer was such for instance, that a timed interval of twentyminutes was indicated, then the motor 35 will run for twenty minutes, ina purely illustrative case, from the time that the switch 38 isfirstclosed, until the motor has moved 'thepointer 22 successively of! fromswitch 38, permitting the latter to open, and onwardly in its "outmovement or stroke until the pointer has been moved to a point on itsrange between "min" at .29 and "max" at 2: respectively, at which the 1running of the motor, and one-hali'of the cycle is completed, with thepointer 22 in the line position.

By the dropping out of the relay controlled by the coil 28, the droppingoi the switch 33 from contact or pole 4|, synchronously andsubstantially' simultaneously engages the switch 83 dotted electricallywith the lower pole or contact it.

This closes a circuit through the in field 35 of the motor, starting thesecond timed half cycle of running of the motor 35, which is onlyterminated after twenty minutes of running time (illustratlvely asbefore) by the attainment by the pointed 22 of th "min position at Ell,accompanied by the closing of the special limit switch 38. This circuit,as should. be clear, is

1 from line Ll, connector 48, conn ctor di, switch .33, contact 34,through in field at of the motor 36, through common return 31 to theline L2.

Obviously, in the circuit thus far described, the system gives a, repeatcycle, which continues to repeat. until interrupted in a suitablemanner. In order to insure a continuanc of the repeated cycles, evenduring the time when the actuating arm or pointer I is at the zero endof its scale or range, adjacent to the side'leg H of the bridge circuit,the preferably small resistance is is provided, which is such as tomaintain a degree of unbalance in the bridge circuit so as to cause atiming cycle of operations of the actuated pointer 22, even when thereis no actual timing cycle indicated by the conditions. Obviously,

, tloning as in ordinary timers. Thus, it is coatempiated that theactuating slidewire ill and its pointer I5 may be relatively moved orhave their resistances varied by manual settings. It is alsocontemplated that the relative position or electrical value of theslidewire arm l5 and the slidewire ill may be accomplished as either amechanical or electrical follow-up" of any other form 0! angular motion,or as functions of the motion or the acceleration thereof, or as morechanges in electrical characteristics, or as a direct coupling to thecondition--responsi 1e member itself.

In the device shown illustratlvely in Fig. 2, a rail an is providedleading over a furnace 51 in which the contents of a scoop 52 are to beheat treated for a time directly proportional to the weight of thecontents 53. A scale Ed is provided leading to a supportingrollingdcvlce 55 on the track '50. The'weight oi the particular load 53:of the material is registered or indicated by the pointer 56 on thedial" 51. Let it be assumed that the pointer to is coupled mechanlcally.or electrically if desired, to the controlling slidewire pointer or armis so that the adjustment of the controlling slide-wire arm is a directfunction of the particular load 53 in the scoop. The timing cycle thusestablished is used to time the duration of exposure of the scoop andits contents to the heat of the furnace, and perfect heating is secured,as should be clear.

In the type of device discussed heretofore, a

. preferred and novel electronically controlled circuit has beendisclosed, but in the broad aspects of this invention, the results canbe approximated by certain mechanical timing assemblies, for which in apurely illustrative fashion reference may be had to Figs. 3 and 4herein. In a Patent No. 1,978,947, issued to J chanson et al. on October30, 1934, there was disclosed an electrically actuated time-controlledcircuit-controller, in which there were two variables as to which timedconthis small timed cycle may be of very short dura- 'tion compared tothe entire range available from the particular system, and simplyinsuresthat the repeat cycles do not come to a complete termination, sothat a further change of condition will find the timer set andoperating.

Of course, it will be evident in the form of invention thus fardescribed, that the gearing and synchronism of the motor will be suchthat there will be a continuous repeat cycle each comprising a stroke orrunning out, followed by an identical but opposite stroke or runningin,"

with the time duration of both being the same so long as conditionsremain the same. In other words, there are preferably always twoidentically timed strokes in a cycle. The cycle can be conat the end ofthe cycle. Similarly, it will be evident that for one-half of thecomplete cycle the relay will beheld in, while for the identicalcomplemental half, the relay will be dropped out, The provision of theupper switch member 29 will permit the establishment of twoidenticallytimed circuit controlling functions during each cycle.

It will be clear that although in the preferred form of the inventionthe actuating arm IS on slidewire in is adjusted as an automaticfunction of a change in condition of some conditioned device with whichit is operatively associated, it will be understod that in the broadestaspects of the invention, the particulartiming derived from tinuous asdescribed, or can be caused to stop invention in this field and has beena highly successful development in the industry. It was a feature of oneform of this invention that all controls were disposed in concentricrelation about a common dial, and that there were manually settabledevices moving about the common axis normal to the dial face, by whichan arm, driven by a reversible synchronous motor, moved between a fixedcontact and a variably positioned contact in a dial-sweeping timedmotion, and so arranged that contact with the adjustably positionedcontact reversed the motor to reverse the sweep of the arm toward thefixed contact. Additional concentric means was provided to control theduration of a circuit that was made at each end of the stroke of themotor driven arm. The disclosure of that patent has been skeletonizedfor inclusion herein by omitting certain portions which areinferentialiy included, in order to show, illustratively, themodifications by which the obiects or this invention can be carried outin amore or less mechanical timer, as distinguished from the electronictimer of the earlier figures. As that timer has been developed inearlier embodiments. the timing cycle was a. function of a manualpresetting.

Referring to the two figures mentioned, a dial till is provided, if,this should be necessary in an automatically functioning device, with. aconcentric axial aperture oi, through which extends the tubulardriveshait 62, driven by the roversible synchronous motor 53, through alost motion connection at. An insulating bushing 65 has change asagainst which the. adjustable time controlling arm 6'! is pressed, andis disposed behind the dial to. The controlling arm El is integralwithor keyed to a pinion gear so so that they turn together, and if desired,an electrical N anism, such iorinsta'nce as them-metallic therconductordisc it, having a soldering terminal j.

H, is disposed upon the bushing 85 in intimate electrical contact withthe pinion gear as and contact arm ill. An insulating disc 12 isprovided for lateral abutment against-the connector lo and is pushedthereagainst to furnish a frictional resistance to movement by acompression spring 113'. engaging between the abutting disc 72 and afixed supporting hearing it. The front of the dial Ed is overhung by acontact-making element is positionable at any desired setting angularlyabout the dial variable in setting as the actuated pinion gear isturned, as will be explained. The protruding frontal portion of thetubular shaft 62 carries the dial sweeping arm id, in electricalconnection with the shaft, and one line from the power circuit extendsthrough the support M and through the tubular shaft 62 to the contactof'the sweep arm it. A fixed contact ii is dis posed at the zero,minimum or starting point of the dial, for instance, in position to beenergized by the sweep arm it at the lower end or com clusion of itsstroke in the second half of its two= part cycle, and contact towherever it happens to be located as a result of a given response to acondition, is arranged to be energized at the upper end of its stroke.

A beam til is provided, which, diagratically, represents an elementwhich ismovab-le as a function of the variation in a given condition ofa conditioned device including any of the conditions to which theelectronically controlled circuit is responsive as described 01' Fig, l.The

. beam. at by any desired condition is caused to sttain a certainposition vertically on its range by acres controlled in its movement onthe voltage divider, by any suitable condition-responsive mechrnallyresponsive element H2. The pointer HI oi the voltage divider H0 leadsthrough a resistance lid to a time-adiustable bleed circuit H5, shuntinga condenser H5 and leading to a grid lid in a triode ill. The plate lidof the tube leads through a relay 120 to line Ll. The cathode i2i leadsto line L2 while being heated by filament 922 as is usual. The timeadjustment lI-i is adjustable to vary the rate of bleed or discharge,and a line i23, containing switch I26, extends between line L2 and thecondenser end of resistance H3, as at I25, It will be understood that asthe voltage divider is-actuated in accordance with a given variablecondition, the arm Hi the value of the'condition, and this value isrepresented by the position of the rack 85 and the angular position ofpinion gear 68 permanently in mesh therewith and moved thereby. Thus,the

' position of the time control arm 61 relative to the fixed contactmember ll, as affecting the time during which the sweep arm is istraversing the dial face between contacts, is a direct function of theinstantaneous value of the condition shooting the beam and rack setting.It will be understood that all reversing functions, circuit controllingfunctions and the like set up in the said patent to Johanson et al.,will be present in the full description of Figs. 3 and but are onlythereof is swung either toward line L2 or line Li. It will be clear thatif it reaches point H6 presses a maximum charge on the condenser, as

will be clear.

With a given condition of the device associated withcondition-responsive element H2, and the arm iii appropriately adjustedas a function thereof, the condenser is charged and remainsappropriately charged and the tube remains conductive so long as switchlZ-l is open. As soon as switch its is closed, a timed interval is begun which maintains during the discharge of the condenser through thetimed bleed shunt during which the tube is hau -conductive. Thedischarge actuates the grid lid and causes plate current to ceaseflowing and relay i2li drops out from the normal non-timing positionshown in Fig. 5'. To secure a controlling function, the relay controls aswitch member I28 which from its engagement with upper contact or poleI30, with whatever circuits, if any, this may control, the switch memberH8 is dropped into engagement with lower pole l3i to control a timedcircuit which lasts until the condenser has been discharged and theplate current builds up and the relay pulls in. It will be clear that avariable timing is secured, due to the variable charging of thecondenser, in turn due to variation in the position ofpointer illrelative to the resistance in voltage divider Ho. The variable timing isalso aflected by the adjustment of the timing adjuster i it governingthe rate of bleed, as will however. that if desired, thecondition-response may be made efiective upon the adjustment 4 forvarying the timed interval with a fixed and constant charge on thecondenser.

It has been made clear that the source ofjthc controlling moment may beany conditioned de-,

preferred in a repeat cycle timer, although ob- I viously other formsof" systems could be availed of for this purpose. Obviously also asingle stop half cycle we complete stop cycle could be secured from themotor devices thus far disclosed. Within the purview of this invention,however, is the purely electronic timer device of Fig. 5..

Referring to Fig. 5, there is disclosed the power iinesLi and L2, havinga voltage'divider convice, and that it is not necessary, with most formsof the inventioh, that the timing assemblyand its control andcontrolledcircuit'sfbelocated, in adjacency to the conditioned device, as it ismerely a matter of length of electrical connectors to separate theactuating and actuated slidewire assemblies in an operative bridgecircuiti'with,

part close to the conditioned device and part-re,- motetherefrom; I i

As a purely illustrative form of device caused to function, by speed orrelativespeed, the" dia grammatic device of Fig. 6 may be consideredtypical.

81 and resistance or slidewire 38 are the exact counterparts oi theactuating slidewire arm I! and slidewire it of the bridge circuit ofFig. 1, and iunction the same.

It will be clear that in the creation of a bridge circuit it is notnecessary that the control he by variable resistances, as variableinductances or the like may also be used'with similar results.

A diagrammatic illustration of this sort of circuit is disclosed in Fig.7. In this typical installation, the conditioned device comprises a flowmeter casing 99, through which fluid flows between inlet iii and exit92, and the float .element 93 supports the floating core 95 through arod 9d, and the core is movable with relation to in the. inductance coil96 having a center tap 9! connecting with the actuated slidewire arm 22of the bridge circuit slidewire is through the primary 2%, as in Fig. 1,and the ends of the inductance coil connect with the slidewire it byside legs ii and id as will be clear. The variation in inductance of theactuator core t5 and inductance t8 causes unbalance of the bridgecircuit, requiring movement, in timed relation, of the slide wire arm 22to balance the circuit, just as inFlg. 1.

As a further illustration of an operative assembly of elements withinthe purview or the invention, reference may be made to the disclosure ofFig. 8, in which a conditioned device is llustrated in fragmental format Hill. A slidewire or the like lill is provided which is identical infunctioning to slidewire Id of Fig. l, a pointer I82 is identical toactuating pointer it of Fig. 1, and is either suitably pivoted formovement (not shown), or may be carried bodily for movement on the freeend of a bellows 863. The latter is in aclosed tubular line- Hi lextending to the sealed bulbous element I05, and the state ofcompression or expansion of the bellows is a funcwhether accomplished bymovement or by purely tion of the internal pressure in the entirebellows system. Normally, with the device illustrated.

the condition in or of the'device ice to which the bellows will respondwill be temperature, but it may equally well be pressure. Any suchassembly or combinations of assemblies of elements to control theactuator of the timer may be resorted to in accordance with thedesired-conditions.

It is an important phase of the invention, that I the entire assembly ofthe timing circuit and re- 'due course, a controlling assembly ofslidewire i0 and arm l5 can subsequently be operatively connected whenthe particular controlling actuating assembly necessary for a giveninstallation,

, whether close to or remote from the conditioned device, and whether itcomprises a variable resistl0 ance, inductance, or any other type ofbridge-circult controlling electrical assembly is provided. Thisuniversality of use is characteristic not only of the disclosure of Fig.l, but also of the electronic timer assembly of Fig. 5.

It'will be clear that it makes no diflerence electrical activity. e

The great range of usefulness and theiull list oi advantages attachingto the invention herein, as well as the fact that the form of inventiondisclosed herein are purely illustrative are not limitative, will beevident, and any change of form or modifications to accord withdcsirements for other exemplifications or the invention are to beconstrued as within the purview of this invention and the scope oi theattached claims, unless'the latter should be otherwise limited.

Having thus described my invention, I claim:

1. A timing" device comprising means automatically movable pursuant to achange of condition of a conditioned device, a timing device having acycle oi operations of variable total length, and means varying thecycle in its total length as a function of the change of condition ofsaid conditioned device.

2. A timing device comprising means automatically movable pursuant to achange of condition of a conditioned device, a timing system comprisinga reversible synchronous motor having cycles of varying length eachcomprised of a stroke out and an equal return stroke in, and meansoperatively associating the said means with the device to vary theduration of the stroke out and therefore of the duration of the returnstroke in as a function of the condition of the conditioned device. I

3. A timing system which comprises in combination a device 01' variablecondition, means of variable setting, means coupling the device andmeans in automatic driving relation to vary automatically said settingwith aid condition, and

'a timing device establishing a timing interval as a function of suchsetting.

4. A timing system comprising a unitary structure comprising athermionic circuit, a relay in the plate output circuit, a reversiblemotor driving in a cons ant repeat cycle of movement, a slidewire of abridge circuit, and a slidewire arm for the said slidewire in drivenrelation to the motor to secure a sweep of the arm relative to the saidslidewire, with a connection controlled by the slidewire arm forcontrolling the thermionic circuit, so arranged that a complementalelectrical unit of variable value can be subsequently attached to theunit to com lete the bridge circuit and the control circuit to thethermionic system, and so that the change or value can be automaticallyeffective upon the said complemental portion of'the bridge circuit tocontrol the timed output of the relay as a function or the change invalue. Y

5. A timingdevice comprising means of variable electrlcal effectivenessautomatically actuataerator cated by the system, movable means arrangedfor operative association with a conditioned dc vice the condition oiwhich is variable relative to a predetermined condition and movableautomatically as the condition of said device varies, and means couplingthe movable means and the adjustable means for synchronous operationwhereby the duration or the timed interval of the sys tem is varied as afunction of the condition of said device.

' 7; A timing system comprising in combination a conditioned devicesubject to change of condition relative to a predetermined condition, a,timing device operative to indicate a timed interval, means in thetiming device for varying the duration of the timed interval, and meansautomatically responsive to changes in condition of the conditioneddevice to synchronously actuate the means in the timing device to effecta timed interval which is a function of the deviation of instantaneouscondition of said conditioned device from said predetermined condition.

8. A timing system having a first and a second slidewire, pointers forthe respective 'slidewire and relatively adjustable thereon between afixed minimum point and a variable maximum point, a transformer having aprimary in circuit with the resnective pointers iorthe respectiveslidewires and arranged to energize the. primary in accordance with theunbalance oi the bridge circuit, means comprising an electronic circuitincluding the secondary of said transformer, a thermionic tube in theelectronic circuit, a double throw relayha'ving an actuating coil intheoutput circuit of said tube, a motor having forward and reversing fieldsand the armature of which is in driving engagement with the pointer ofsaid second mentioned 'slidewire in both directions of runningcontrolled by said respective fields, an electrical networlsincludingthe contacts of the relay and the respective fields of the motor and soarranged that when the actuating coil of the relay is energized acircuit is closed through the forward field of the motor andwhen'deenergized a, circuit is closed through the reversing field of themotor, means for relatively adjusting the pointer on the-first mentionedslidewire between the minimum and maximum points thereon to neouslyopens the circuit through the forward held of the motor and closes acircuit tmoush the reversing field thereof and the pointer of the secondslidewire is movedin a timed interval complemental oi the firstrelatively to the second slidewire until it again attains its initialminimum position, and means for indicating the total time intervalcomprised of the forward stroke and the complemental reverse stroke ofthe pointer for the second slidewire as the timed interval of the timingsystem. I i

9. A timing system as recited in claim d, char-- acterized by theprovision oi supplemental switch means for energizing the coil of therelay to re verse the direction of running of the motor when the pointeroi the second slidewire reaches its minimum point in the reversedrunning of the motor, for initiating a repetition oi? the timing runningof the motor forward and reverse in a repetition of said total timinginterval.

1.0. In a timing apparatus arranged for opera;- tive association with asource of electric poten tiai. a bridg circuit comprising a pair oi no--tentiorneters connected in parallel acrom such source when ogerativelyassociated therewith and each having a contact adiustahle thereover, a

bridge output circuit connected between said ad '1 ,iustable contactswhereby voltage from such oneratively associated source is impressedacross said output only when said contacts are not simition to oscillatesaid motor=driven contact at a constant speed between a predeterminedinitial position and the position of zero bridge circuit output asdetermined by the position of said arbitrarily adjustable contact,whereby the position establish a timing interval when the slidewire Iuntil the pointer of the second slide'wire has moved iromits minimumpoint relatively on the slidewire to a point atwhich the bridge circuitis balanced and the actuating coil or the relay is deenergized, andwhich substantially instantaof the latter determined the time said motoropcrates in each directionin each cycle oi its oscillatory motion.

11. In a timing apparatus as recited in claim 10, said network includinga working circuit, and means in said network for automaticallycontrolling said working circuit as a function of the time of running ofthe motor in one direction 12. In a timing apparatus as recited in claim10, means in said network ior automatically reversing said motor toinitiate a repeat cycle of running to oscillate said motor-drivencontact between its said predetermined position and the position of zerobridge circuit.

13. In a timing apparatus as recited in claim wamm was none.

